Tilt-up building construction is well known in the construction industry. Tilt-up thin-shell construction is a method of construction where the walls or panels are formed horizontally on a building slab or foundation from light gauge metal framing embedded in thin (1.5″ to 2″) concrete. Thin-shell construction is distinguished from traditional tilt-up construction which uses steel rebar inside of 6″ to 8″ thick concrete walls, rather than thinner concrete with external steel. There are obvious advantages to the newer thin-shell systems in material savings and ease of transporting and handling lighter panels. When the panels are dried and finished they are simply tilted up to become vertical walls.
Another method employs pre-fabrication of the building panels that can be either constructed on or off-site and then moved into a specific position to form the walls, floors and roofs of a building structure These pre-fabricated panels are reinforced and joined to each other by metal studs and joists embedded in the panels.
It is generally recognized that the overall strength of a prefabricated building panel is, in large part, dependent upon the integrity of the bond that is created between the metal stud and the concrete panel after the concrete has hardened. For example, a stud edge surface in simple contact with the surface of the concrete panels results in a relatively weak bond and, therefore, a relatively weak panel. Accordingly, it has become a common technique to provide projections on the edge of the metal stud that extend into the wet concrete therefore securely anchoring the metal stud to the concrete panel when the concrete hardens.
By way of example, projections can be provided directly on the flange of a metal stud to anchor the stud to the panel. In one know method, the metal stud is shaped like a common “C” channel and has a planar central web and a pair of substantially perpendicular edge flanges. However, one edge flange has a series of spaced, longitudinally shaped cut-outs along its length, thereby permitting the cut-out portion of the edge flange to bend upwards and form a projection which can be embedded within the concrete material of the panel. A reinforcing mesh or the like can be mechanically attached to the projections so that the mesh is positioned at the proper depth within the panel. The drawback with these cutouts in the studs is that common “C” channel must be either specially modified or specially manufactured which adds to the cost of labor and material of the finished panel. One solution is the SteelCrete Punch Press available from Simple Building Systems, Inc., 27280 Jefferson Avenue, Suite 202, Temecula, Calif. 92590. The SteelCrete Punch Press has a series of hydraulic punches that when a length of C channel is inserted into the press, the cutouts or tabs are punched and formed. The problem with this system is that the SteelCrete Punch Press is so large that it is prohibitive to take to the job site, because of the heavy Punch Press the studs have to be shipped twice. From the stud manufacture to the Punch Press, unloaded, punched, reloaded and shipped to the client. This extra shipping and handling significantly raises costs. Additionally, the higher cost of this press makes it not feasible for the smaller scale contractor.
Simple Building Systems, Inc. does supply pre-punched studs however, since the studs are specially modified or manufactured at an off-site manufacturing facility, the studs are not readily susceptible to further modifications or adjustments to meet unusual or special needs which may arise in the field.
Pre-punched studs also suffer from the additional storage space requirements and difficulties in stacking and shipping. With the pre-punched studs, the cut outs created prevent orderly stacking, increase the required volume for materials storage, are easily damaged or bent and make the normally linear metal stud difficult to handle.
Prior methods of forming metal studs for use with tilt up construction include sequentially cutting and then shaping tabs on metal studs. Such methods are generally not portable and not usable at a job site, as the linear travel required to have both cutting stations and shaping stations in sequence mechanically requires a travel greater than the width of a conventional vehicle and trailer. As the metal studs being punched may be of any length, it is desirable to be able to punch the studs in a manner so as not to interfere with a vehicle towing a punching unit, making prior art portable units impractical.
Another potential solution is described in a patent issued to Ruiz et al., U.S. Pat. No. 5,414,972 where a reinforced structural member is a two-piece assembly comprising a structural member and a reinforcing member. The reinforcing member is fastened to the structural member such that a series of projections extend from the reinforcing member are engaged in the building panel. Although this is a partial solution to the shipping problem, since less material is shipped, it requires significant additional labor to fasten the reinforcing member to the structural member raising costs.
Accordingly, there exists a need for a system and method of manufacturing a structural member that is a modification of a standard C channel metal stud used in the manufacture of thin shell tilt-up style construction panels that is easily and economically punched to form the tabs needed for embedment and attachment to the concrete.
Further there is a need for a system of economically punching tabs in a C channel metal stud that is compact, simple to operate and portable such that it may be readily used on a job site.